The present invention relates to a drum brake shoe, particularly for a motor vehicle, and to a drum brake equipped with this shoe.
A drum brake in general comprises a fixed backplate which is perpendicular to the axis of a drum that rotates as one with a wheel, and which supports shoes fitted with arc-shaped friction linings. A cylinder-actuated main control is able to push these shoes radially outward and press the linings against the cylindrical interior face of the drum that rotates as one with the wheel, in order to brake this wheel.
To create a parking or hand brake, an additional control is provided, this comprising a cable pulled by a lever actuated by the driver. The cable slides in a sheath the end of which bears against the backplate, the end of the cable acts on a lever which pivots and multiples the force to expand (part) the shoes and apply the linings firmly against the drum.
A drum brake of this type, described in document FR-A1-2841619 comprises a device for quickly and reliably attaching the end of a cable blind to a brake lever comprising a drum that has already been fitted.
The end of the cable bears an end terminal introduced from the outside into a hole in the backplate and which slides along a duct formed at one end of the lever, at the same time pressing against a leaf spring which flexes. When the rear part of the end terminal reaches the end of the duct, the leaf spring pushes the end terminal to engage the cable in the duct. The end terminal is locked in position by the leaf spring and allows the lever to be pulled.
To remove the cable during a maintenance operation by movement in the opposite direction to the direction of fitting it. This removal is tricky to perform because the lever is located behind one of the shoes and the movement that has to be performed is fairly complicated as the operator cannot see the end terminal and does not have direct access thereto.
It is a particular object of the present invention to alleviate these disadvantages and to provide a simple, effective and economical solution to the removal of the hand brake cable.
To this end, the invention provides a drum brake shoe, this shoe comprising a rigid web and a cylindrical part that bears a friction lining, characterized in that an interior edge of the web has a cut-out providing access to a brake cable attachment end terminal.
One essential advantage of the drum brake according to the invention is the ease with which the brake cable can be removed, thanks to the cut-out in the web of the shoe which allows the cable attachment end terminal to be seen and accessed.
This cut-out has a depth extending over approximately half the width of the rigid web of the shoe and a length at least equal to its depth.
It has inclined sides such that its open end is far wider than its closed end.
It is near one end of the shoe which is capable of pivoting by bearing against a stop connected to the backplate of the drum brake.
One inclined side of the cut-out may meet this end of the shoe.
The invention also relates to a drum brake, particularly for a motor vehicle, which is fitted with a shoe of this type.
Advantageously, in this brake, one end of a lever is connected by a pivoting connection to that end of the shoe on which a main control acts and the brake cable is attached to the other end of the lever.
The brake cable slides in a sheath the end of which bears against the backplate of the brake and the cable end terminal can be attached to the lever blind when the drum is assembled.
Advantageously, to do that, that end of the lever that is attached to the cable ends in a bent tab forming a duct the axis of which is parallel to the backplate, the edge of the tab being inclined and which diverges from the axis of the duct towards the drum, the lever also comprising a ferrule for guiding the end terminal when the cable is being fitted. During mounting, the end terminal slides along the inclined edge of the duct, pressing against an elastic leaf. When the rear face of the end terminal reaches the end of the inclined edge of the duct, the elastic leaf pushes on the end terminal to engage and hold part of the cable in place in the duct.